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The Gem · Modular UV sensor
The90™ Gem Gold
One sensor. Endless ways to wear it. A precision UVA and UVB sensor disguised as fine jewelry. It reads the light your skin actually gets and powers your Sun Score in the app.
UVA + UVB tracking
Splash-proof
7+ days battery
Bluetooth pairing
iOS + Android
1-year warranty
$299
Finish
Gold
or 4 payments of ~$75 with Shop Pay.
Free shipping · 30-day returns · 1-year warranty · No subscription · Ships in 1–2 business days.
Introducing
The90™ Gem. One Gem, worn your way.
The Gem is the sensor. The way you wear it is up to you. It clips into the pendant and necklace today, with a hat clip, bag tag, and more on the way. Your day changes; your Gem keeps up.
Available now: Pendant · Necklace
Coming soon: Hat clip · Bag tag · More to come
Future-proof
The Gem you buy today is the least it will ever do.
New accessories. Smarter guidance through over-the-air algorithm updates. Buy the sensor once, and it keeps getting more useful over time. A gadget goes out of date. A platform grows with you.
Sun protection that finally protects you.
Sunscreen, hats, shade, SPF clothing. You’re doing the work. The Gem closes the loop by measuring what they’re actually preventing.
Everything rolls up into your Sun Score.
The app aggregates every reading into one number, your Sun Score, built from the live metrics below.
The Sundial
A live, dynamic graphic of your current UVA and UVB intensity, streaming from the Gem to the app.
The Burn
Your personalized countdown to your daily limit, built on your skin type, your sunscreen, and your live UVB exposure.
Skin Aging Zone
Daily accumulation of UVA, the deep-penetrating rays responsible for up to 90% of visible aging.
Designed as jewelry
Technology you’d actually wear.
Engineered as fine jewelry, not a fitness tracker. The Gem blends into your everyday stack, from workdays to workouts to weekends in the sun.
Choose your finish:
Gold
Specs and details.
Tech specs
What’s in the box
Shipping & returns
Warranty
Try it through a season of sun.
30-day returns
Don’t love it, send it back.
1-year warranty
Covered against defects.
Free shipping
On every order.
No subscription
The app is included.
Loved at first light.
“It’s the first wearable I actually want to wear. The pendant reads as jewelry, full stop.”
Claire D. · Early access reviewer
“I swapped it between the pendant and my bracelet in seconds. The modular idea just works.”
Priya S. · Early access reviewer
“The reapply alert caught me twice on vacation. No burn for the first summer in years.”
Hannah W. · Early access reviewer
Frequently Asked Questions
Do I have to wear it on a necklace?
When will the hat clip / bag tag ship?
Can I wear it in the shower or pool?
How accurate is it?
Is it FSA/HSA eligible?
Is there a subscription or monthly fee?
No. Your Gem comes with the full The90 app and every core feature, with no monthly fee to read your own light. You buy the sensor once.
What does The Gem actually measure?
It reads the UVA and UVB reaching your skin, separately and in real time, then turns the day into a single Sun Score from 0 to 100. Along the way it tracks the light you want, like your morning circadian light and your estimated vitamin D, and the exposure you want to manage, like the UVA that ages your skin.
Do I have to wear it as a necklace?
It comes as a jewelry-grade pendant on a matching gold or silver chain, so you can wear it out of the box. The Gem is also a removable core, so it can move into new ways to wear it as they launch, including a hat clip and bag tag on the way.
How is this different from the UV Index or my weather app?
The UV Index gives one number for a whole city and says the same thing to everyone. The Gem measures the light actually hitting your skin, separates the aging rays from the higher-energy ones, and reads it against your personal skin profile in real time. It is the difference between a forecast and your actual day
Can I wear it in the water?
Rain, sweat, and a quick rinse are all fine. The Gem is water resistant to 1 meter for 30 minutes, so leave it off for the pool, the shower, hot tubs, and saunas.
What if it is not for me?
Try it for 30 days. If it is not right, send it back for a full refund, and every Gem is covered by a 1-year warranty. Free shipping, dispatched from California within 1 to 2 business days, currently within the US.
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